The present invention relates to a small cooling fan used to radiate the heat from a heating component, such as a microprocessing unit (hereinafter referred to as an MPU) in a personal computer or other electronic equipment.
Generally, an electrical apparatus, such as small electronic equipment including a multi-functional and high-performance personal computer, incorporates an MPU, as a functional part thereof. However, this MPU generates heat and is destroyed by the heat at temperatures more than approx. 90xc2x0 C. Thus, the MPU is equipped with a cooling device to radiate the heat generated in the MPU and provide safety for the electronic equipment.
A desired cooling device is of a small type. However, a typical cooling module that has heat radiating fins cannot provide sufficient cooling. Therefore, a cooling device has been proposed that has a small cooling fan as a main constituent component and is formed as a cooling module, as shown in a partially cutaway perspective view of a conventional cooling module in FIG. 4 and a plan view thereof in FIG. 5.
This cooling device is structured as a so-called cooling module. A heat receiving section 5 having a heating component 4, e.g. an MPU, joined thereto is joined to a flat cooling fan 3. The cooling fan has a housing 1 made of a die casting using heat-conductive aluminum, and a rotating fan 2 housed therein. A heat radiating section 6 having heat radiating fins is joined to the air outlet side of cooling fan 3. The cooling device has a heat sink effect as a cooling module. Moreover, the wind generated by the rotation of rotating fan 2 forcedly cools the fins in heat radiating section 6 to which the heat of heating component 4 has been transferred. Thereby, heating component 4 radiates heat and cools down.
Now, in a recent notebook personal computer, the operation of the MPU and other components at high frequencies is necessitated by image processing and other purposes, thus involving heat generation at high temperatures. It is difficult to cool the heating components with the above-mentioned cooling device sufficiently. Especially in the cooling fan, backflow of the wind is likely to occur at the air outlet of the housing. Thus, such a loss of airflow quantity and static pressure hinders sufficient cooling of the fins in the heat radiating section. Therefore, the cooling fan cannot drastically lower the temperatures of heating components, e.g. an MPU, which process data at high frequencies for image processing. In addition, there is another problem. Sufficient cooling requires a large cooling fan. It is difficult to use a large cooling fan as a cooling device for a notebook personal computer.
The present invention provides a small cooling fan comprising:
a rotating (rotary) fan body with a vane that is provided in a fan housing;
an air outlet provided on one side of the fan housing; and
an air channel for backflow prevention provided outside of the vicinity of the tip of the vane of the rotating fan body and extending to the air outlet.